Two Ways to Modify Datsun 510 Cars in Forza Motorsports: Traditional and Pro-Street

 June 9, 2022

#449

Gentle reader,

I have been simulation racing for a number of years now. Nothing serious, console-based, but always with a steering wheel and pedals, shifting for myself. Just like driving my real rides. My car has a six-speed manual transmission. 

Speaking of driving, I've been doing that for almost fifty years. As a kid I knew what I wanted "to be" when I grew up: An auto mechanic.

So, I attended tech school in the afternoons of my junior and senior high school years. In the mean time, I got a job at a Mobil station. Or rather, a job reached out to 16-year-old me.

I came home to find a note, written by one of my sisters, to call, "Urmer Bosim". I had no idea what or who that was. Turns out, he spelled his name, Ermer Bocim. He called himself, "A Polack and proud of it."

He was the owner of said Mobil station and a customer who attended our church recommended me to him. I never found out who that was.

But, I digress. I do that sometimes. THIS article is about one of my favorite activities involving one of my favorite cars, real and virtual. The 1970's Datsun 510.

It was the little brother of the iconic 240Z. A sedan, or wagon version of the sports car having 2/3rds (1.6 liters) of the 2.4 liter six cylinder engine of the Z car. Four-wheel independent suspension (except the wagon), unheard of in an economy car then. Front disc brakes too.

And yes, I drove a real one. A two-door in kind of an orange color. Manual transmission, of course. Dad needed an economical car to commute over the weekends to and from Washington, D.C. We had a 510 on the used car lot at the Chevy dealer I worked for. He bought it. On weekends, whenever possible, I was canyon carving in Dad's car.

These are 1/24th scale models of two Datsun 510s. The one on the left is the same model and color of my Dad's, but Pro-street. To the right is another Por-Street car, but painted up in the livery of one of the winningest SCCA racers back in the day.

The first 510 diecast I bought was a kit. Little did I know, that it had no interior, only the hood opened, AND, it did not include a complete engine. No ignition system and only two cylinders representing the two carburetors that should be there!

This is a photo of JDM twin Datsun 510 carburetors and their intake manifold. These have aftermarket (not stock) air filters on them. So, imagine twenty-four times smaller and plastic versions attached to the engine above.

So, I bought this model which has a later model (and turbocharged) Nissan DOHC engine in it. A common upgrade in the field of Pro-Street.

Although this is only a molded one-piece representation of the engine bay, it too has a similar engine. Plus a strut brace.

SO, getting back to modifying the cars in Forza Motorsports. I have always modified the stock Datsun 1.6 liter SOHC engine just as the racers did back in the day. I go no higher than B Class (from F) with the car. 

Believe it or not, this is a MODEL engine bay of the BRE Datsun 510 SCCA racer! SUCH detail! Those are twin Weber two-barrel carburetors on it. No air filters as race cars often do not have them.

The engine is kind of buzzy at higher RPMs, and the car could be faster at the top end. BUT, the car is so LIGHT to begin with, and with full roll cage and removing all the unneeded weight, it is even lighter, so I always stuck with the stock engine. Kind of a purist.

I thought about it and finally decided to try an engine swap making everything else the same, except the wheels. Check out the performance specs below.

This is the Benchmark Page for the car with the SOHC engine. Note the specifications. Good acceleration, great cornering, but it tops out at just under 140 MPH.

Now, the DOHC four cylinder engine's specifications, above.

The zero-to-sixty acceleration time is DOWN by 1.339 seconds. Yet, the Zero-to-one hundred time is faster by 0.413 of a second. Not much, for sure, but it's a difference. And you KNOW, from racing how much of a difference seconds make in race results.

Now, look at the cornering figures. The red, white and blue BRE Datsun has cornering ability OVER one G. Yet, the engine swapped 510 cornering ability is way down!

Why? They have the same width, diameter and type of tires on both cars. The wheels are different, but both weigh about the same. So, un-sprung weight is not a factor.

The answer? TRACTION. The twin-cam DOHC engine, while still in B Class is much more powerful than the fully modified stock SOHC engine. Resulting in a TOP speed of almost TWENTY miles an hour higher!

The rear tires, despite my having installed a limited slip differential, just cannot get a grip with "normal" race acceleration! I found that I had to "roll onto the accelerator pedal, rather than nailing it with this engine.

I had not even test driven a 510 with this engine before, but took it right to the FULL Twin Ring Motegi circuit for the B Class championship races. 

I immediately discovered the wheel spinning and lack of cornering ability and restarted the race after the second corner.

I was easy on the throttle until the car was going well. I kept it in at least third gear on all the corners. The DOHC engine's torque was strong enough to accelerate in third with minimal wheel spin. I found that the car PULLED away from the other AI cars on every straight, but they often caught up to me because I had to corner slowly and carefully to avoid excessive oversteer. I was able to make 2.22 laps doing that. 

"OK," I thought, "Let's hire a driver and see how the AI does." Riding along in the 2nd heat, the AI was often shifting all the way down to first in the slower corners, even though the car was traveling forty or more MPH at the time. Not something I often do unless the car is in a really low (F or E) class. The AI found that it had to immediately upshift to second each time. Nonetheless, it was past all the other cars ahead of it by the end of the first lap and won the race with a 2.19 lap time.

While on the subject of TOP SPEED. I have ALWAYS installed front spoilers/splitters and rear spoilers/wings on my cars. ALWAYS. Yet, there is one drawback to doing so: TOP SPEED.

Those wind cheaters, while providing downforce to aid in higher cornering speeds, ALSO cause DRAG which results in ten to twelve or more MPH SLOWER top speeds. 

On some small tracks, that makes no difference. But on courses with long, high speed straights, it makes a HUGE difference. 

Go ahead, try this experiment for yourself. See what your results are. Especially top speed. 

HERE are the CAR modifications I ALWAYS do: Race brakes, lowering the car fully, stiffening the suspension with the heaviest anti-sway-bars. Full roll cage. Completely removing all excess weight. The lightest flywheel. Race clutch. Full-race six-speed sequential race transmission. Carbon fiber driveshaft. Two-way rear differential. 

Then, depending upon the class I am trying to keep it in, I then start modifying the engine. Beginning with: Fuel Injection. Race intake. Race Exhaust. Then, depending upon how high a class I am taking it to, other engine modifications. I rarely do engine swaps. But if needed, I supercharge or turbocharge the engine with a race Intercooler.

IF, you chose to let Forza do quick class upgrades, that's fine. But, my history of having been a mechanic and a longtime racer, it gives me joy to modify the cars with my own choices. 

I would rather race a fully-modified (but still IN class) OLD car, such as a Chevy Corvair, or VW Karmann-Ghia, or Datsun 510 or 240Z (Fairlady) than choose any puddle-jumper front-wheel-drive economy car. Plus, it really pisses off the AI cars when I show up in my racy old car. Seriously, they crash into me right at the start of the races!

Thank you for taking the time to read this article. I LOVE simulation racing, but am fully aware of my limits and thus happily stay with Forza Motorsports 4 on the Xbox 360.

Scott Robb

June 9, 2022

#449